But if that doesn’t deter you, Debra Jaliman, M.D., a top dermatologist in New York City and author of Skin Rules, suggests Mavala Stop, a clear nail polish that you can pick up at most drugstores for around $13. Wear it alone or as a mani top coat and the sharp, bitter taste makes your tongue feel tingly–almost itchy–on contact. Very effective and totally harmless, Dr. Jaliman assures.